Difference Between Protozoa and Helminths

Protozoa vs Helminths

Protozoa and helminths are two major groups of organisms acting as parasites and are able to cause various infections to humans. In definition, parasites are the organisms that live in or on other organisms (called host), and are capable of damaging the host. This biological relationship or the phenomenon is known as parasitism. These main parasitic groups include both multicellular and unicellular organisms. The study of these parasites is called parasitology. Usually parasites have complex life cycles, and thus, they re quires more than one host to complete their life cycles. There are three types of hosts available, namely; reservoir host, intermediate host, and definitive host.

What is Protozoa?

All the protozoa are unicellular eukaryotic organisms and possess well-organized nuclei. In addition to nuclei, all of them possess other organelles including Golgi complex, mitochondria, ribosomes, etc. Most of the protozoa are free-living and have various types of vacuoles in their cells. These organisms are living as trophozoites or vegetative forms. However, most of the protozoa are capable of encystation, which enables them to survive in harsh environmental conditions. Parasitic protozoans are mainly classified into three phyla, (a) Sarcomastiyophora, which includes the protozoa that possess flagella or pesudopodia or both types of locomotor organelles in any stage of their life cycle, (b) Apicomplexa, which includes the organisms with apical complexes, (c) Ciliophora, which contains the protozoan that possess cilia or ciliary organelles in at least single stage of their life cycle. Some examples for protozoa are Trypanosoma, Giardia, Entamoeba, Babesia, and Balantidium. Some infections caused by protozoa include malaria, amebiasis, trypanosomiasis, etc.

What are Helminths?

Parasitic helminths are multicellular organisms, and their approximate body size may vary from 1 mm to 10 m. The infection of helminths can be either through the direct ingestion of their eggs, or penetration of the skin by their larval stages, or transmission of life cycle stages to hosts via insect vectors. Parasitic helminths are well adapted to living and surviving in their host’s body. The outer structures of the body of helminths show some remarkable adaptations in order to protect their internal organs from the host protective mechanisms. Clinically important parasitic helminths are classified into three groups; (a) Nematodes , which includes the roundworms such as Ascarislumbricoides, Enterobiusvermicularisetc, (b) Cestodes, which consists of tapeworms like Taeniasaginata, Diphyllobothriumlataetc, and (c) Trematodes, which contains flukes like Clonorchissinensis, Schistosomamansoni, etc.

What is the difference between Protozoa and Helminths?

• Protozoa are unicellular, whereas helminthsare multicellular.

• Protozoa can be only observed through microscopes, whereas helminths are usually seen with naked eye.

• Protozoa have the ability to multiply within their definitive host, but in general helminths are not capable as such.

• Protozoa have indefinite life span, whereas helminths have definite life span.

• Life cycle of helminths has stages of adult, egg and larva, whereas no such stages exist among protozoa.


Further Reading:

  1. Difference Between Algae and Protozoa
  2. Difference Between Protozoa and Protista
  3. Difference Between Protozoa and Bacteria